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Types of memory

a) WM

a) Declarative
- episodic
- semantic
- autobiographical

b) Non-declarative
- procedural


Procedural learning

- Rule based learning in which performance facilitation occurs with practice on a task with NO need for conscious awareness i.e. can eventually, after practice, perform the task without thinking


Procedural learning
how to test?

1) Tower of London: the colour one
Winter et al. (2001)
- Not a measure of implicit procedural learning as it suggests = it involves declarative processes; and these are of fundamental importance to the task.
- Use declarative strategies to do solve the task
- Hippocampal Amnesiacs tend to show impairments on this task bc their explicit memory for declarative strategies in the task is compromised

2) Serial Reaction time task:
- RTs show a selective decline to predictable targets as compared with random targets, this difference reflecting procedural learning.

- The serial reaction time test (SRT) has been validated as a measure of procedural learning in studies of normal and brain-damaged subjects (Pascua l-Leone et al., 1993)
- Considered an implicit task bc even when people are learning it they’re unaware that they are (Green et al. 1997)

- as its only RT thats looked at, interpretation of which component is learnt is difficult and disambiguation of implicit and explicit processes problematic
- Affected by impulsivity (ADHD) (Robbins & Crockett, 2010)


Neural Basis of procedural learning

- Basal ganglia (striatum)
- Cerebellum
- Frontal cortex (receives afferents from the BG and cerebellum)

Impaired PL using variants of the serial reaction time task:
A. Parkinsons (Doyon et al., 1997)
B. damage to the cerebellum (Doyon et al., 1997)
C. Patients with prefrontal lesions show impaired PL on the SRT (Gomez et al., 1999).
D. In healthy people, procedural learning was associated with increased activation in the thalamus, medial frontal lobe, and cingulate gyrus (Kumari et al., 2002)

^ this experiment used SZ as a comparison group; BUT SZ are not always impaired with procedural learning; differences come from the tasks used. (Zedkova et al. 2006)


working memory WHAT + who?

Baddeley & Hitch, 1974
What =phonological loop, visuospatial store and central executive + episodic buffer


localisation of the central executive? (6)

Dorsolateral prefrontal cortex: central executive:

A. Some suggested that it is the site of working memory storage - comes from studies that show delay period activity in dlpfc in fmri (Courtney, 1994)


B. Lesions to dlpfc don't always affect WM storage (D’Esposito and Postle, 1999)

C. Postle (2006) - NOT a storage site but, contribution of dlPFC to working memory could be any of the CONTROL processes (e.g., attentional selection, flexible control, etc.) that are also required when performing a working memory task.

D. Lara & Wallis (2014) - trained monkeys to remember 1 or two coloured squares.
Found = little evidence that the dlpfc maintained colour information in WM. But found that the monkey was making microsaccades when there was 2 colours (shifting attention between the two when eyes on fixation) & suggested that the activity in the dlpfc encoded attentional control signals that helped improve the animals’ performance.

(Petrides et al., 2012) -- precise localization of working memory functions cannot be directly exchanged from monkeys to humans due to significant interspecies anatomical differences

Barbey et al. (2013); lesion studies
- Dlpfc is important for manipulation of representations (lesions to dlpfc impaired performance on letter-number sequencing (audWM) & spatial span backwards) (visuo-spatialWM)
-- both validated measures of WM, EG Crow (2000) (WMS-III) BUT they also show that some of the variance explained on LNS = visuospatial tasks - impaired performance may come from**
PROB bc MCI is not spatial tasks (E.G Huntley, 2010)


Double-dissociation of verbal and spatial memory

A) There may be a hemispheric dissociation for verbal and spatial WM (Smith & Jonides, 1997)

** Nystrom et al., 2000 didn't tho
utilized spatial stimuli that were more amenable to verbal encoding strategies (variant of the n-back task but with letters)


Verbal working memory

Cogan (2017)
- Storage and rehearsal are different operations

A. Ravizza et al. (2004) -- parietal lobe & Broca's area involvement in an n-back task; rehearsal and storage

B. Meta analysis (Becher, 1999) - huge variability in storage localisation w PL ambiguously involved

A. Chein & Fiez (2001) – fMRI during recall task
- Broca's --> signal was higher when 3 syllables (vs 1). ARTICULATORY REHEARSAL
- Parietal --> little bit more activity when similar BUT evidence was not significant (suggestion of storage?)

BUT Buchsbaum & D'esposito (2008) & they
- they suggest that parietal involvement is NOT wm
- they point out that those who don't find significant parietal activation use recall tasks > Recognition tasks (n-back)
- Recognition tasks can use 2 strategies for identification. Familiarity & rehearsal.
- SO they pertain that parietal involvement might actually be the parietal lobe switching strategies --> another part of the CE.

Mottaghy et al. (2002) – n-back recognition task (why they found parietal involvement)
- Tms + VWM
- Bilateral involvement of the MFG and inferior parietal lobe
- they suggest that the bilateral involvement (rather than just the left IP, Collette, 2002) is bc the right contributes to the CE.
- Suggestion of: Distributed CE network
- but ofc may have been bilateral = CE.

C. Muller & Knight (2006)
- Broca's aphasia often display a rehearsal deficit too
- Normally associated with lesions of Broca's area


Spatial working memory

Jonides et al. (1993) – PET
- Block design.
- Dots appeared, try and remember these dots over a 3 second delay. After 3 seconds a probe would appear where one of the dots was or somewhere else -> in same place as initial dot?
- Substraction approach
- Diffuse network (parietal gyrus/IFG/premotor/occipital)
Parietal = spatial attention?

PROBLEMS with block design - Honey (2000)
1. repeated presentation of similar stimuli = fatigue/autonomisation/habitutation

2. may become predictable - anticipation (b/c cant be randomised have to be related stimuli)

3. "blocked" = have examined neural activity changes on the order of tens of seconds. This time scale is decidedly inappropriate for the selective investigation of the neural substrates of cognitive processes that occur within seconds or milliseconds of others.

4. subtraction method assumes that adding one cognitive process to another doesnt affect the first one + that its the sum of both (i.e. their perception condition vs memory - the activity is taken as localisation of storage) but memory/perception could affect perception/memory

Event related designs circumvent such problems...

Postle, Zarahn & D'Esposito, 2000
- didnt use block related design --> event related fmri (allows u to look @ over milliseconds)
- Partial out the variance due to one condition (E.G. due to cue & response) while looking @ delay condition - allows you to look at only the activation from one condition (doesn't use subtraction)
(Zarahn et al. 1997) --> subtraction doesn't work for some brain regions - other factors i.e. attention may be adding to the activation = false positives.

- Found greater activation in caudate nucleus during spatial tasks

- Griffin (2015) -- cooperative interactions during spatial tasks with hippocampus & caudate nucleus
- RE is the pivotal link between the hippocampus and the prefrontal cortex + involved in spatial WM/EF = involved in the the ability to hold and manipulate spatially relevant information for brief periods of time.
***more of a network**


Declarative memory how to measure? + EVAL

** Rey Auditory verbal learning test: 15 words, 5 trials. Participant recalls as many words as possible after each trial including words recalled in earlier instances

- Mitrushina et al. (2005) -- age, gender and IQ affected
- involves WM: Fard et al. 2016) – if have a problem with STM/WM then likely to not be very good @ this task E.G. ADHD, dyslexia, specific language impairment, and reading and mathematical difficulties (E.G. Archibald & Gathercole, 2007).
- insensitive to depression and anxiety - with scores that do not differ meaningfully from healthy peers (e.g., Davidoff et al., 1990)
- Sensitive enough for Alzheimer’s (Salmon et al. 2002)


Medial Temporal Lobe & Declarative Memory --> what is the medial temporal lobe made of ?

A) Hippocampal formation
B) Amygdala
C) Entorhinal cortex
D) Perirhinal cortex
E) Parahippocampal gyrus


Semantic declarative memory - what and where?

what?: Knowledge acquired about the world, such as general facts.

1. some found more activity in hippo C and entorhinal C for recent vs remote semantic mems (Haist, 2001)
2. Others havent found any difference (Bernard, 2004)

A. Smith & Squire (2009)
- some have found more activity in the hippocampus or entrohinal cortex during recollection if recent semantic memories compared with remote semantic memories.
** The study of recent and remote memory with neuroimaging presents a number of challenges**
1. when participants retrieve memories from the PAST they are also incidentally encoding the questions that they are asked AND the recollections that they produce. Accordingly, during retrieval of past memories brain activity related to encoding might mask or override brain activity related to retrieval of recent versus remote memory.
(Smith, 2009)
2. the memories that are retrieved from different time periods might differ not only in age but also in their vividness or richness. SO, a finding of greater brain activity for recent than for remote memories might be related more to the greater vividness or richness of recent memories than to their recency per se (Gilboa et al., 2004).
3. a finding of greater brain activity for recent than for remote memories might be due to tendency for more recent semantic memories to be associated with personal, episodic recollections (rather than age)

a. directly evaluating the effect of memory age independently
b. evaluated the effect of memory age independently of the effect of memory richness
c. we asked whether recent memories (but not remote memories) tended to be associated with episodic recollections

FOUND = brain activity in the hippocampus during recall of semantic memories decreased as the memories became more remote


Hippocampus & the permanent consolidation of memories (Episodic/autobiographical)

Mckenzie (2011)
- Activation of the hippocampus during accurate episodic memory retrieval in normal subjects was at its highest for most recently stories & declined over approximately over 9 years (parallel with retrograde amnesia)
- Conversely, activation of wide spread cortical areas was lowest for most recent accurately remembered events & increased for more remote memories

Steinvorth et al. (2015) FOUND CONSTANT HIPPOC activation BUT noted that hemodynamic activation (fmri) reveals one aspect of the engagement of a structure. In contrast, the behavioural effects of MTL lesions identify the tasks where the MTL makes an essential contribution....
The prompting method = will activate the hippoc i.e. prompting before the test - make the remote memory recent which may activate the hippocampus (Recent retrieval, however, destroys the remote character of memories because each time one remembers an event one encodes it anew (Buckner et al., 2001)

Patient H.M.
a) HM had retrograde amnesia only for things nearer to the event BUT childhood memories were intact (he had gross MTL damage) (+ anterograde amnesia)
- As time passes memories rely less on the MTL

b) Patient R.B.
- suffered a small stroke in the temporal lobe
- marked anterograde amnesia but with only an extremely mild retrograde amnesia, extending back just two years
- damage was restricted to just the CA1 field of the hippocampus


- other patients produced fewer details about past events, even events from early life (Rosenbaum et al. 2005)

Knutson (2015)
- all four patients had significant damage to the posterior temporal cortex in Rosenbaum (2005)
- Lesions that extend lateral to the medial temporal lobe, for example, could impair remote memory by damaging regions thought to be repositories of long-term memory.


Neurotest for memory - complex figure

Complex figure test – Osterrieth, 1944
a. draw a figure immediately or after a delay or both.

- Age affected scores (older performing much worse)
- No gender differences (Fastenau, 1999)

- Qualitative errors are most likely to occur in recall drawings of patients with frontal lobe damage (inc. TBI)
- Parkinson’s patients have very poor recall scores (Ogden, 1990) known for WM problems
- Mild cognitive impairment = performed below controls in recalling the figure// As did a group @ risk of dementia (Kasai et al. 2006)
- Relies heavily on on executive functioning (Wantabe et al. 2007); planning (ADHD//Korsakofs) (Mason et al. 2013)


n-back task

- not purely a measure of WM
- Also relies a lot on processing speeds (Miller, 2009)
- Parkinsons (known wm deficits) did worse than controls on the n-back task. BUT it detected the slower RT of PD in n-back. But this sample didnt differ on digit span backward (known WM task)
= WM + processing speeds